K2, the world's second highest mountain, in the Himalayas mountains range of Pakistan Photograph: EPA

Wilco van Rooijen takes the bandages off his feet and shows me his frostbitten toes. They are hideous - black slugs with squashed bloody bits in the middle like mangled pizza. There are still five toes on each foot, but probably not for much longer. "Those two will go," he says, pointing to the toes next to the big one on either foot. "And probably a bit of the big toes. That's what worries me. The big one is for balance. I'd have to learn to walk again." It would also, presumably, mean the end of his career as a mountaineer.

I ask him how he feels. "Really good," he says. "I have no fever, and I also have no nightmares. So actually, I'm doing fine." He knows how lucky he's been.

Van Rooijen led one of the teams tackling K2 which was caught in the biggest climbing catastrophe of recent times. Eleven died - some slipped to their deaths, most were struck by huge blocks of ice. Van Rooijen's team got off lightly - of the five who set out one turned back; one, the Irishman Gerard McDonnell, died; and three survived. McDonnell's boots were seen flying through the air in the snow and ice. His body was not found.

Van Rooijen, 40, was stuck for three days at the top of K2. The world's second highest peak, bordering Pakistan and China, is known as the Savage mountain - only 305 people have reached the top and at least 76 people have died attempting to negotiate it, most on their way down. By rights, Van Rooijen should be dead. The cold should have seen him off, or the lack of oxygen, and it was a miracle he didn't slip.

We meet at his tiny house in Utrecht, in the Netherlands. His 10-month-old son, Teun, is playing with Van Rooijen's wheelchair, and his teacher wife, Halaan, is tending the invalid's needs with a great deal of love and a fair bit of exasperation. What did she think when she first saw his feet? "Awful. Really awful. Painful and smells, everything. But he's still alive, and that's the main thing."

Van Rooijen looks tanned and healthy and is remarkably upbeat. He tells the story as if it's an old tale he's been banging out for years. It's only after a couple of hours you notice that he's going over and over the same ground, trying to make sense of it all.

As a child he loved walking in the Alps with his parents. When he was 16 he started climbing, and wanted to know everything there was to know about ropes and knots. He did a degree in electronics and prepared to follow his father into engineering, but he knew it wasn't for him. Instead, he worked with friends fixing houses to subsidise the climbing trips. Eventually he stopped working as an electrician, devoted himself to climbing and supported himself by travelling the country giving companies motivational speeches.

He told them how he had tackled the north pole, the south pole and Everest. And most of all, he told them about the first time he attempted K2 in 1995. They always preferred the disaster stories. That time, a boulder smashed his face and his arm. "I hardly survived. A big stone smashed my face and my arm. People see me with a bloody face and they are shocked. They think this is not just a walk in the mountains, this guy is crazy. Then I start to explain that if you are ambitious there is a lot of risk."

Another trip to K2 was inevitable. "I had this drive to prove to all the people around me that I could do K2, that I can climb Everest without oxygen, that I can go to the north pole, that I can survive for 80 days on the south pole." He clicks his fingers as he counts off each challenge. "A lot of people didn't believe me. Maybe because of this I had this stubborn thing; I will show you."

The first time he attempted K2 he had just got together with Halaan. How did she feel about it? "You can ask him the questions. I'm not commenting." Which seems to be an answer in itself.

"She thought it sounded exotic back then," he says, "but she didn't know anything about peaks. It sounded romantic, and there was media attention. But then when it went wrong she was very scared and said, 'I hope you never do this again'."

He went back in 2006 with McDonnell. That time the Irishman was hit on the head and broke his skull.

What is the thrill in climbing? "It's a milestone. You can say your whole life, 'I was there'. When you talk about it, you get this, I don't know how you say it in English, this shivering." He points to the hairs on his arms. "If you are there. Pfffff." He blows on his teeth in awe. "And you are fighting for each other, taking care of each other - to survive this it gives you a soulmate. The rest of your life you can always knock on the door. They will always be there to help you."

I tell him it seems like a death wish. Ach, he says, that's the anti-climbing lobby for you. All you hear about are the dangers. "It's always in the media when people are killed. But if it's a successful story, nobody's interested. To the summit this time, it was all perfect, and then all the way down, it's this big story because of the tragedy."

I find myself laughing. Come off it Wilco, I say, you can hardly expect news stories saying, "Climbers have lovely time at summit. PS 11 killed".

He smiles, and concedes it's unlikely. Yes, he says, the risk is part of the attraction. "People do think we are crazy, but we also think a lot of people around us are spilling their lives by doing nothing. My mother, my father, they died from cancer. My mother was eaten away by this disease, and for her the quantity of life was the most important thing. She was 63 when she died. For me, it's about quality. Maybe you don't get old, but it doesn't matter to me."

When he left for K2 in May Teun was only seven months old. Did that make the decision tougher? "Yes, of course. But you just have to put things in compartments and concentrate on the job in hand."

It was on the way up that he witnessed his first death on the mountain. A Serb climber detached himself from the rope to pass another climber and fell. "You think, fuck it is not possible, because it is getting very stupid." He clicks his fingers again. "And gone. "First he slips, then he tumbles over then he's gone. It's some kind of slow motion. You think, give me your hands, then he's gone. Aaaah! Just like that. Then you realise, fuck he must be dead. Then you see some movements on the glacier and everybody is shouting he's still alive." But he wasn't. Minutes later the Serb's high-altitude porter also fell.

Van Rooijen's team reached the summit. Two of his partners descended that night to the lower altitude of camp 4. But by the time Van Rooijen was ready to go, the avalanche had cut the ropes and they could not go. It was late, the temperature was falling, and he was trapped in the "death zone" above 8,000 metres (26,000ft) with four other climbers, including McDonnell.

Next day, the clouds had descended on the mountain, making it almost impossible for the climbers to see each other. Somehow Van Rooijen managed to descend the perilous "bottleneck" where so many of the others met their deaths when hit by the ice. But by now he was snow-blind, delirious and frozen. He lost his way. He had his satellite phone, but couldn't read the numbers of his team-mates. He hallucinated - hearing voices and seeing imaginary people who didn't rescue him. Then he came across three real people and wished it was another hallucination - three Koreans, tangled in their ropes, hanging upside down, dying. Only one could talk and he asked for clothes to keep warm.

Amazingly, Van Rooijen survived another night. Did he give up hope? "I thought, nobody knows I'm here, it's bad weather, no helicopter can get here. Probably I gave up. I thought if I moved, I'd fall. There was no solution."

Van Rooijen is a Christian, but he says he didn't pray or think about his family. "It was just pure focus. I was only thinking about surviving. I was too busy to pray. If I had prayed then it would have meant I'd really given up."

Next day he was even weaker. He fell asleep for a couple of hours. "I'm not sure if it was tiredness or that I lost consciousness." When he woke up, the clouds parted, and he spotted a gully. Through that he managed to make an escape, and unwittingly headed for his camp. His team spotted him. Despite the frostbite he managed to get back to base camp, where the helicopter picked him up.

What amazes me is how calm he is less than three weeks later. It seems as if the frostbite is emotional as well as physical. Perhaps the enormity of it will suddenly hit you, I suggest. "No, I don't think so, because as a mountaineer you know these things can happen." He says that if and when his feet recover he will climb more 8,000-metre mountains, and that even though it is awful that so many people died this expedition will be good for business - this disaster will easily out-disaster his previous visit to K2 and all the businessmen will love to hear about it.

What about his ambitions for the future? For once, Halaan answers. "To build a farm. We have just bought a farm."

He hobbles over to his computer on his heels to show me his pictures.

What was it like when you reached the summit? "It was the most beautiful thing. At the top you're looking over maybe 100 mountains. The earth is not horizontal any more, it makes a curve. You see this beautiful round planet earth. Gerard had tears in his eyes."

He shows me the pictures and they are the most stunning scenes imaginable - climbers at the top of the world, heads in the perfect blue sky. And he talks about all the people up there that they befriended: the Norwegian newlyweds - the wife saw her husband fall to his death; the experienced French climber set on returning to France until Van Rooijen convinced him to stay because good weather was forecast and it would be his chance to complete K2 - he and his high-altitude porter died.

He shows me the picture of McDonnell, grinning, waving his Irish flag. And them all hugging in joy. "You see Gerard, standing there, this huge man with a big smile on his face. There was not a moment when we were thinking of tragedy. Everything was according to plan."

He clicks on to pictures showing a trail of blood, then two sherpas horribly contorted in their ropes. "One of the sherpas had reached the summit, and the next day his wife gave birth. And this Norwegian couple is still in my mind." He is haunted by their stories. "They were a really lovely, adventurous couple. And now if you know these people didn't survive. Why? It's very ... yah. Such beautiful weather, everything was OK ..." And he stares at the picture of the Irishman who was to die a few hours later and finally the words stop coming.